At least 10 fishermen were missing after four boats capsized in rough seas off Malappuram district, police said on Monday.
One boat with six fishermen from nearby Ponnani coast is said to have capsized near Nattika in Thrissur district.
"The Coast Guard has been pressed into action to rescue the fishermen," the police said.
In another incident on Ponnani coast, two fishermen were missing after their fibre boat overturned in mid-sea, they said.
Rescue operations have begun.
In yet another incident, three out of five fishermen who put out to the sea from nearby Tanur coast have swum to safety off Parappanangadi.
A search is on for the two fishermen who were missing, the police said.
The Coast Guard officials reported that another fishing boat that set out to sea from Ponnani coast with six fishermen was stranded in mid-sea near Ernakulam due to engine failure.
Another boat from Vellayil in Kozhikode sank but the fishermen swam to safety early Monday, Coast Guard officials said.
Marine enforcement is taking stock of the situation.
On Sunday, weathermen said Kerala may experience heavy rains and winds due to the low pressure formed in the Arabian sea.
In view of the prediction of rough seas, Chief Minister Pinarayi Vijayan had appealed to fishermen not to venture out to sea for 48 hours beginning Sunday.
Despite the warning, the fishermen set out to sea.